Injection molding elongated probe having integral heating element and locating means

Abstract

This invention relates to a hot tip gated multicavity injection molding system wherein an elongated heated probe extends centrally in a straight portion of the melt passage leading to each gate in a position wherein a tip end of the probe is centrally aligned adjacent the gate. One part of the straight portion of the melt passage is formed by a locating sleeve which is seated in the cavity plate and has spaced pins which extend inwardly to contact the outer surface of the probe to accurately locate the probe with the tip end in central alignment with the gate. Each probe has a central heating element with a double thickness portion extending to provide additional heat where the pins contact the probe. One of the pins is hollow to receive a thermocouple to measure the temperature of the melt flowing past the pins. Another part of the straight portions of the melt passage is formed by a cylindrical spacer collar which extends between the manifold and each locating sleeve to provide an insulating space of a curtain width between the manifold and the cavity plate.

What I claim is: 
     
       1. In an injection molding system having an elongated heated probe and a melt passage which extends to convey pressurized melt from a heated manifold to a gate in a cavity plate leading to a cavity, the heated probe having a generally cylindrical outer surface and a forward tip end, the heated probe being mounted to extend through the manifold and centrally axially into a straight portion of the melt passage which leads to the gate, said melt passage being substantially larger in diameter than the heat probe, the heated probe extending to a position wherein the tip end of the heated probe is adjacent the gate and the melt flows around the probe longitudinally to the gate, the improvement wherein; a locating sleeve having a forward end and a rear end is seated in the cavity plate in coaxial alignment with the straight portion of the melt passage, the sleeve having a central bore extending axially therethrough which is equal in diameter to and forms part of the straight portion of the melt passage with the heated probe extending centrally therethrough, the locating sleeve having a plurality of spaced locating means extending radially inward into the central bore to contact the outer surface of the probe to accurately locate the probe centrally in the straight portion of the melt passage with the tip end of the probe in central alignment with the gate, at least one of the locating means being partially hollow to receive a thermocouple therein to measure the temperature of the melt flowing past the said one locating means.   
     
     
       2. An injection molding system as claimed in claim 1, wherein the locating means are pins which extend inwardly to locate the probe. 
     
     
       3. An injection molding system as claimed in claim 2, wherein the pins are located adjacent the forward end of the locating sleeve. 
     
     
       4. An injection molding system as claimed in claim 2, having a spacer collar extending axially in alignment with the rear end of the locating sleeve, the spacer collar having a central bore which is equal in diameter to the central bore of the locating sleeve and also forming a part of the straight portion of the melt passage, the spacer collar having a rear end seated in the manifold and a forward flanged end abutting against the cavity plate to provide a space of a predetermined width between the manifold and the cavity plate. 
     
     
       5. An injection molding system as claimed in claim 2, wherein the probe has a central heating element which is bent back upon itself to provide a double thickness portion which extends along at least a portion of the probe where the pins contact the outer surface of the probe.